Question: If $a + b + c = -7$ and $x + y + z = -8$, what is $-2x - 3a - 2z - 3b - 3c - 2y$ ?
Explanation: $= -3a - 3b - 3c - 2x - 2y - 2z$ $= (-3) \cdot (a + b + c) + (-2) \cdot (x + y + z)$ $= (-3) \cdot (-7) + (-2) \cdot (-8)$ $= 21 + 16$ $= 37$